In wiper blades for windows of motor vehicles having elongated, rubber-elastic wiper strips which are pressed against the window to be wiped and which is retained on a support element that has an elongated, bandlike spring-elastic retaining rail, the retaining rail is intended to assured the most uniform possible distribution, over the entire field swept by the wiper blade, of the contact pressure of the wiper blade on the window, which pressure originates in the wiper arm. Because of an appropriate curvature of the unstressed retaining railxe2x80x94that is, when the wiper blade is not resting on the windowxe2x80x94the ends of the wiper strip, which in wiper blade operation are placed fully against the window, are urged by the then-tensed retaining rail toward the window, even if the radii of curvature of spherically curved vehicle windows differ in each wiper blade position. Accordingly, the curvature of the wiper blade has to be somewhat greater than the greatest curvature measured in the field to be swept of the window to be wiped. The retaining rail thus replaces the complicated support bracket construction with two spring rails, disposed in the wiper strip, of the kind used in conventional wiper blades.
In a known wiper blade of this type (German Patent Disclosure DE-OS 26 14 457), the connection device is integrally joined to the retaining rail. Accordingly, it is made of the same material as the retaining rail. This may be of only secondary importance, as long as the retaining rail is made of a plastic and is produced by filling a suitable mold. If the retaining rail is to be made of metal, however, two diametrically contradictory demands are involved. That is, first, the retaining rail must have good spring properties; second, however, the extensions of the connection device must be bent by about 90xc2x0 out of the plane of the retaining rail and fixed in that position without problems, so that the loads between the wiper blade and the wiper arm can be absorbed on stop faces of these extensions. These two demands are practically impossible to meet, unless disadvantageous compromises in terms of the choice of material are made.
In another known wiper blade (German Patent Disclosure DE-AS 12 47 161), the retaining rail is provided with a connection device embodied as a separate component. This connection device is solidly joined to the retaining rail with the aid of rivets. The requisite bores in the retaining rail, however, lead to an undesired, because uncontrollable, change in the retaining rail tension, making a satisfactory wiper outcome unattainable.
In the wiper blade defined by the body of claim 1, conversely, a choice of material that meets the demands made of each component can be made for both the retaining rail and the connection device. The joining of the two components to one another is done without problems and inexpensively by forming the connection device onto the prefabricated retaining rail. The forming-on is attained by placing the retaining rail in a casting mold or injection mold, which after closure is filled with a plastic that meets the demands. The retaining rail is then provided with the required connection device, and no further assembly steps are needed. Experiments have shown that by the forming on of the connection device, a sufficiently solid connection is made between the connection device and the retaining rail.
An especially reliable connection between the retaining rail and the connection device is attained if the connection device is provided with clawlike extensions, which at least intermittently clasp the two side longitudinal edges of the retaining rail and rest on the band face, toward the window, of the retaining rail.
If the retaining rail is provided with shoulders, with which counterpart shoulders of the connection device are associated, then an absolutely immobile connection, secured against shifting, is obtained between the retaining rail and the connection device, because counterpart shoulders occur automatically in the molding of the connection device and cooperate with the shoulders of the retaining rail.
The shoulders can be embodied in simple way at apertures and/or recesses open at the edge and/or shaped hooklike features of the support element.
A further improvement in the fastening of the connection device to the retaining rail is achieved by roughened features, which are provided at least on the surfaces of the retaining rail that are oriented toward the connection device.
An especially compact wiper blade is obtained if the retaining rail is made from a metal.
In order to provide the retaining rail with a connection device for the wiper arm in an economical way and in the process ideally satisfy the contradictory demands of the retaining rail and the connection device, a fastening method according to the invention is used, in which the prefabricated retaining rail is placed in a mold, which after closure is filled with hardenable plastic, so that after the mold is opened, the finished support element can be removed.
Further advantageous refinements and embodiments of the invention are disclosed in the ensuing description of an exemplary embodiment shown in the associated drawing and in a drawing figure that explains the claimed and described production method.